The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
During vehicle running, exhaust gas emitted, resulting from combustion of fuel contains regulated emissions that are harmful to human body or can contaminate atmosphere, which are generated depending on conditions of vehicle running. Notable regulated emissions include carbon oxides, nitrogen oxides and the like.
In order to reduce emissions of these regulated materials, vehicles are equipped with a variety of exhaust purification devices or apparatuses, in particular, a selective catalytic reduction (SCR) device for removing nitrogen oxides (NOx) existing in exhaust gas.
The SCR device is a device for removing NOx substance by injecting urea solution into exhaust gas containing the NOx substance to form a mixture of urea solution and exhaust gas and allowing the mixture to be subjected to chemical reaction in the process of passing through a catalytic device to change into water and nitrogen.
Meanwhile, in case of such SCR device, as the more uniform a mixture ratio of the urea solution and the exhaust gas is, the more the performance of removing the NOx substance is enhanced, improving the performance of mixing the urea solution and the exhaust gas in the SCR device is an important task to enhance the performance of the exhaust purification device for reducing the NOx substance.
As the foregoing described as the background art is just to promote better understanding of the background of the present disclosure, it must not be taken as an admission that it corresponds to the prior art well known to those who have ordinary skill in the art.